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Advances in Fingerprint Technology.pdf

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visualization of latent f<strong>in</strong>gerpr<strong>in</strong>ts, and also provide some of the reagent<br />

formulations and procedures used.<br />

Powder Dust<strong>in</strong>g<br />

The simplest and most commonly used procedure for latent f<strong>in</strong>gerpr<strong>in</strong>t development<br />

is powder dust<strong>in</strong>g. Powder dust<strong>in</strong>g is a “physical” method of enhancement<br />

that relies on the mechanical adherence of f<strong>in</strong>gerpr<strong>in</strong>t powder particles to<br />

the moisture and oily components of sk<strong>in</strong> ridge deposits. Application of powder<br />

to latent pr<strong>in</strong>ts by brush<strong>in</strong>g is a simple technique and yields <strong>in</strong>stantly apparent<br />

pr<strong>in</strong>ts, but it also has disadvantages. Contact of the brush with the f<strong>in</strong>gerpr<strong>in</strong>t<br />

ridges has an <strong>in</strong>evitably destructive effect. The use of f<strong>in</strong>gerpr<strong>in</strong>t powders dates<br />

back to the early n<strong>in</strong>eteenth century. In general, there are four classes of f<strong>in</strong>gerpr<strong>in</strong>t<br />

powders: regular, lum<strong>in</strong>escent, metallic, and thermoplastic.<br />

Regular F<strong>in</strong>gerpr<strong>in</strong>t Powders<br />

Traditional F<strong>in</strong>gerpr<strong>in</strong>t Powders<br />

Regular f<strong>in</strong>gerpr<strong>in</strong>t powders consist of both a res<strong>in</strong>ous polymer for adhesion<br />

and a colorant for contrast. Hundreds of f<strong>in</strong>gerpr<strong>in</strong>t powder formulas have<br />

been developed over the years. A detailed discussion of f<strong>in</strong>gerpr<strong>in</strong>t powder<br />

formulas and their preparations can be found <strong>in</strong> the first edition of Scott’s<br />

F<strong>in</strong>gerpr<strong>in</strong>t Mechanics 1 and <strong>in</strong> the report by Goode and Morris. 6 Follow<strong>in</strong>g<br />

are some of the most commonly used f<strong>in</strong>gerpr<strong>in</strong>t powder formulas:<br />

Black F<strong>in</strong>gerpr<strong>in</strong>t Powder Formulas:<br />

Ferric oxide powder<br />

Black ferric oxide 50%<br />

Ros<strong>in</strong> 25%<br />

Lampblack 25%<br />

Manganese dioxide powder<br />

Manganese dioxide 45%<br />

Black ferric oxide 25%<br />

Lampblack 25%<br />

Ros<strong>in</strong> 5%<br />

Lampblack powder<br />

Lampblack 60%<br />

Ros<strong>in</strong> 25%<br />

Fuller’s earth 15%

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